The present invention relates to an oxide-containing silicon-carbide-based inorganic fiber or a crystalline silicon-carbide-based inorganic fiber which is excellent in oxidation resistance at high temperatures, in particular at high temperatures in an atmosphere containing moisture, and the production processes of these. Further, the present invention relates to an oxide-containing organosilicon polymer used as a raw material for producing the above silicon-carbide-based inorganic fiber, etc., and its production process.
A silicon-carbide-based fiber is used as a fibrous reinforcement for plastics or ceramics owing to its excellent heat resistance and mechanical properties. And, many proposals have been already made with regard to silicon-carbide-based inorganic fibers and the process for the production thereof.
For example, JP-B-58-38535 discloses a process for producing a silicon carbide fiber, which comprises spinning an organosilicon polymer having a chain formed of silicon and carbon as main components, heating the spun fiber at a low temperature in an oxidizing atmosphere to form an infusible fiber and calcining the formed infusible fiber at a high temperature.
Further, JP-B-62-52051 discloses a silicon-carbide-based inorganic fiber composed of silicon-carbon-titanium-oxygen, and JP-B-58-5286 discloses a process for producing the above silicon-carbide-based inorganic fiber composed of silicaon-carbon-titanium-oxygen, which comprises spinning a polytitanocarbosilane obtained by bonding part of silicon atoms of a polycarbosilane to titanium atoms through an oxygen atom, infusibilizing the spun fiber and calcining the infusibilized fiber.
In recent years, as typified by ceramics reinforced with an inorganic fiber, a composite material reinforced with an inorganic fiber is required to endure being used in severer environments. Therefore it is desired to increase an inorganic fiber as a reinforcing material in heat durability under an oxidizing atmosphere, in particular under an atmosphere containing moisture.
It is an object of the present invention to provide an oxide-containing silicon-carbide-based inorganic fiber or a crystalline silicon-carbide-based inorganic fiber which is excellent in oxidation resistance, in particular in an oxidizing atmosphere containing moisture at high temperatures, as compared with the silicon-carbide-based inorganic fibers disclosed in the above publications, an oxide-containing organosilicon polymer used as a raw material for producing the above fibers, and the production processes of these.
According to the present invention, there is provided an oxide-containing organosilicon polymer which is characterized by containing 1 to 45% by weight of metal oxide particles.
According to the present invention, further, there are provided an oxide-containing silicon-carbide-based inorganic fiber which is characterized by containing 1 to 45% by weight of metal oxide particles and a silicon-carbide-based inorganic fiber in which the content ratio of the metal oxide in a region close to the surface of the fiber is higher than the content of the metal oxide in the inside of the fiber.
According to the present invention, further, there is provided a production process of an oxide-containing organosilicon polymer, which process comprises adding an alcohol solution of a metal oxide sol to an organosilicon polymer and heat-treating the mixture in an inert gas atmosphere.
According to the present invention, further, there is provided a production process of an oxide-containing silicon-carbide-based inorganic fiber, which process comprises adding an alcohol solution of a metal oxide sol to an organosilicon polymer, heat-treating the mixture in an inert gas atmosphere to obtain an oxide-containing organosilicon polymer, melt-spinning the oxide-containing organosilicon polymer to form a spun fiber, infusibilizing the spun fiber to obtain an infusible fiber, and calcining the infusible fiber under heat.
According to the present invention, further, there is provided a crystalline silicon-carbide-based inorganic fiber containing 1 to 45% by weight of a metal oxide and having a calcined structure of SiC.
According to the present invention, further, there is provided a production process of a crystalline silicon-carbide-based inorganic fiber containing 1 to 45% by weight of a metal oxide and having a calcined structure of SiC, which process comprises adding an alcohol solution of a metal oxide sol to an organosilicon polymer, heat-treating the mixture in an inert gas atmosphere to obtain an oxide-containing organosilicon polymer, spinning the oxide-containing organosilicon polymer to form a spun fiber, infusibilizing the spun fiber to obtain an infusible fiber, calcining the infusible fiber under heat to obtain an oxide-containing silicon-carbide-based inorganic fiber, and heat-treating the oxide-containing silicon-carbide-based inorganic fiber at a temperature of from 1,600 to 2,100xc2x0 C. in an inert gas.